Compare structures of two databases?

Question

I wanted to ask whether it is possible to compare the complete database structure of two huge databases. We have two databases, the one is a development database, the other a production database. I've sometimes forgotten to make changes in to the production database, before we released some parts of our code, which results that the production database doesn't have the same structure, so if we release something we got some errors. Is there a way to compare the two, or synchronize?

Solution 1

For MySQL database you can compare view and tables (column name and column type) using this query:

SET @firstDatabaseName = '[first database name]';
SET @secondDatabaseName = '[second database name]';

SELECT * FROM  
  (SELECT
      CONCAT(cl.TABLE_NAME, ' [', cl.COLUMN_NAME, ', ', cl.COLUMN_TYPE, ']') tableRowType
    FROM information_schema.columns cl,  information_schema.TABLES ss
    WHERE
      cl.TABLE_NAME = ss.TABLE_NAME AND
      cl.TABLE_SCHEMA = @firstDatabaseName AND
      ss.TABLE_TYPE IN('BASE TABLE', 'VIEW')
    ORDER BY
      cl.table_name ) AS t1
LEFT JOIN                     
  (SELECT
      CONCAT(cl.TABLE_NAME, ' [', cl.COLUMN_NAME, ', ', cl.COLUMN_TYPE, ']') tableRowType
    FROM information_schema.columns cl,  information_schema.TABLES ss
    WHERE
      cl.TABLE_NAME = ss.TABLE_NAME AND
      cl.TABLE_SCHEMA = @secondDatabaseName AND
      ss.TABLE_TYPE IN('BASE TABLE', 'VIEW')
    ORDER BY
      cl.table_name ) AS t2 ON t1.tableRowType = t2.tableRowType
WHERE 
  t2.tableRowType IS NULL        
UNION 
SELECT * FROM  
  (SELECT
      CONCAT(cl.TABLE_NAME, ' [', cl.COLUMN_NAME, ', ', cl.COLUMN_TYPE, ']') tableRowType
    FROM information_schema.columns cl,  information_schema.TABLES ss
    WHERE
      cl.TABLE_NAME = ss.TABLE_NAME AND
      cl.TABLE_SCHEMA = @firstDatabaseName AND
      ss.TABLE_TYPE IN('BASE TABLE', 'VIEW')
    ORDER BY
      cl.table_name ) AS t1
RIGHT JOIN                     
  (SELECT
      CONCAT(cl.TABLE_NAME, ' [', cl.COLUMN_NAME, ', ', cl.COLUMN_TYPE, ']') tableRowType
    FROM information_schema.columns cl,  information_schema.TABLES ss
    WHERE
      cl.TABLE_NAME = ss.TABLE_NAME AND
      cl.TABLE_SCHEMA = @secondDatabaseName AND
      ss.TABLE_TYPE IN('BASE TABLE', 'VIEW')
    ORDER BY
      cl.table_name ) AS t2 ON t1.tableRowType = t2.tableRowType
WHERE 
  t1.tableRowType IS NULL;

If you prefer using tool with UI you can also use this script https://github.com/dlevsha/compalex which can compare tables, views, keys etc.

Compalex is a lightweight script to compare two database schemas. It supports MySQL, MS SQL Server and PostgreSQL.

Screenshot (compare tables)

Solution 2

You can use the command line:

mysqldump --skip-comments --skip-extended-insert -d --no-data -u root -p dbName1>file1.sql
mysqldump --skip-comments --skip-extended-insert -d --no-data -u root -p dbName2>file2.sql
diff file1.sql file2.sql

Solution 3

To answer this kind of question currently, I've made a script that uses information_schema content to compare column, datatype, and table

SET @database_current = '<production>';
SET @database_dev = '<development>';
-- column and datatype comparison
SELECT a.TABLE_NAME, a.COLUMN_NAME, a.DATA_TYPE, a.CHARACTER_MAXIMUM_LENGTH,
    b.COLUMN_NAME, b.DATA_TYPE, b.CHARACTER_MAXIMUM_LENGTH
FROM information_schema.COLUMNS a
    LEFT JOIN information_schema.COLUMNS b ON b.COLUMN_NAME = a.COLUMN_NAME
        AND b.TABLE_NAME = a.TABLE_NAME
        AND b.TABLE_SCHEMA = @database_current
WHERE a.TABLE_SCHEMA = @database_dev
    AND (
        b.COLUMN_NAME IS NULL
        OR b.COLUMN_NAME != a.COLUMN_NAME
        OR b.DATA_TYPE != a.DATA_TYPE
        OR b.CHARACTER_MAXIMUM_LENGTH != a.CHARACTER_MAXIMUM_LENGTH
    );
-- table comparison    
SELECT a.TABLE_SCHEMA, a.TABLE_NAME, b.TABLE_NAME
FROM information_schema.TABLES a
    LEFT JOIN information_schema.TABLES b ON b.TABLE_NAME = a.TABLE_NAME
        AND b.TABLE_SCHEMA = @database_current
WHERE a.TABLE_SCHEMA = @database_dev
    AND (
        b.TABLE_NAME IS NULL
        OR b.TABLE_NAME != a.TABLE_NAME
    );

Hope this script can also help people that looks for a non-application solution, but the usage of script. Cheers

Solution 4

You can just dump them with --no-data and compare the files.

Remember to use the --lock-tables=0 option on your production database to avoid the big nasty global lock.

If you use the same mysqldump version (your dev and production systems should have the same software, right?) then you'll expect to get more-or-less identical files out. The tables will be in alpha order so a simple diff will show discrepancies up easily.

Solution 5

For mysql on Linux, it is possible via phpmyadmin to export the databases without 'data' and only structure.

Scrolling through the export options for the entire database, just deselect 'data' and set the output to text. Export both databases you wish to compare.

Then in file compare in your preferred program / site, compare the two text file outputs of the databases. Synchronization is still manual in this solution, but this is effective for comparing and finding the structural differences.

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